土壤中氯离子对无溶剂环氧石油沥青涂层的腐蚀行为

为考察无溶剂环氧石油沥青涂层在不同氯离子浓度土壤中的腐蚀行为,采用电化学测试技术的方法测试涂层的腐蚀电位和低频阻抗模值.结果表明,随着土壤中氯离子含量的增加,涂层的腐蚀电位负移,容抗弧半径减小,阻抗模值降低,说明土壤中氯离子含量的增加导致涂层对土壤中腐蚀性介质的屏蔽作用能力有所下降.400 μm厚的涂层在29% H2O+1.8% NaCl土壤中的交流阻抗谱图呈现单容抗弧特征,随着埋设时间的延长,阻抗模值下降,埋设360 d时涂层的低频阻抗模值达到8.3020×108 Ω？cm 2,涂层未发生鼓泡、裂缝和剥落迹象.表明涂层形成了有效的屏蔽层,对基体金属有着良好的防护作用.
To analyze the corrosion behavior of solvent-free coal asphalt coating in different chloride ion concentration, the corrosion potential and the low frequency impedance modulus of the coating were tested by electrochemical technique. Results show that with the increase of chloride ion content in soil, coating corrosion potential negative shift, capacitive reactance arc radius and the impedance modulus value reduce, which indicates that the increase of chloride ion content in soil will lead to a decrease in the shield ability of the coating to the corrosive medium in soil.The EIS of coating with 400 μm immerses in soil of 29% H2O+1.8% NaCl appears only one capacitive reactance arc. With the extension of time buried, the impedance value decreases, and the resistance is 8.3020×108 Ω？cm2 for 360 days.There is no signs of bubbling, cracking and spalling,which shows that the coating forms the effective shielding layer with a good protective effect on matrix metal.